How Worried Should You Be? Petrol in a Diesel Car in Old Stratford
Provided it has not been started, worry far less than you probably are. Everyone around Old Stratford starts with "have I ruined it?", and the fair answer is generally no: petrol resting in the tank of a diesel remains harmless until priming, cranking or driving draws it into the system. Petrol in Diesel is who to call, with the engine kept off, and so it stays that way. What petrol actually does to a diesel, how to judge how far it's gone, and how to stop it from happening a second time: that is the remainder of this page.
Inside your engine: what petrol in a diesel does
Two jobs fall to diesel on its journey round a motor. It protects to begin with, and only then does it burn. What keeps the surfaces inside the high-pressure fuel pump and the injectors from grinding against each other is your diesel passing through them — they are made to very fine clearances.
Of these two jobs, petrol manages the first badly and the second not at all. It is runnier than diesel and strips away the protection your fuel system hinges on, so a pump running on a petrol mixture is a pump wearing itself. And petrol is made to resist igniting under compression, which is the reverse of what a diesel needs from its fuel. That's where the knocking comes from.
The shape of the trouble is clear when you put those together. The damage is done by movement, not by contact. All a tank with petrol in it amounts to is a fuel problem. The beginning of a mechanical problem is a pump that has been running on that petrol — and whatever a worn pump sheds travels on with the fuel to the fuel injectors beyond it.
Old Stratford, petrol in a diesel: four cases, from mild to serious
Fuelled, and never started: nothing beats it. Being at a forecourt is what makes this possible: elsewhere, the car has been driven there to begin with. With the petrol held in the tank alone, it is drained and cleaned on the spot, and nothing more is needed.
A brief spell of running, or merely your ignition on. Your system has been primed, so petrol has left your tank and got to the filter and your lines. Usually little more than clearing, rinsing and sorting the filter, and so still simple.
Those few miles driven were your pump running on fuel weakened by petrol throughout. The work is the tank, the lines, the filter and clean fuel through the entire circuit, and how hard the vehicle was driven matters as much as how far. The school run to Old Stratford Primary School is one matter. A run as far as Milton Keynes, under 5 miles away, is a very different task. So is any distance on the M1, under 5 miles from Old Stratford, where your engine has been labouring hard the whole time.
Driven on till it complained — clattering, smoke, an uneven idle, a soft throttle. That is the motor telling you its fuel has stopped behaving like diesel. Leave it where it has stopped: a lay-by, a quiet street, the verge on Cosgrove Road. A car pulled over early very rarely has lasting damage, because the fuel drain and the flush-through, which still come first, take care of it.
Petrol in a diesel myths Old Stratford motorists hear
"Top it up the rest of the way with diesel and it'll be fine" — a myth. It won't. Nothing comes out when you top up — the tank simply carries more of the same blend. The idea behind that guidance — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a newer diesel copes with a bit of petrol. Rather, the opposite. More precise components and higher pressure are how a modern diesel runs its fuel, and that makes the lubrication matter more, not less.
One myth that catches motorists out: if it starts and drives, it must be unharmed. Feed diesel to a petrol motor and it generally will not run, so the driver stops — and the damage stops with them. Feed petrol to a diesel and it generally starts, ticks over and pulls away like nothing has happened — all while its pump wears. A running engine does not mean fine.
An outdated workaround for a distinct problem lies behind this one. Myth: "Add some two-stroke oil and drive the car home." What petrol has diluted stays thinned, and that petrol remains in your tank regardless.
"Drain it yourself and you are sorted" — a myth, because after it has been running some petrol lies in the filter and lines, waiting to go right back through your pump on your next start. It is also genuinely risky to drain petrol into a can at the kerbside.
How it happens: petrol in a diesel
A careless moment is seldom the cause, and nobody means to do it. The forecourt makes it simple: the petrol nozzle is the slimmer of the two, and it slides into a diesel filler with almost no resistance, while a diesel nozzle mostly will not go into a petrol motor at all. So the mistake runs one way.
It happens when routine and your car stop matching. A new car, a hire car or a courtesy car. Two motors on one drive, one petrol, one diesel. The pumps in a different order on a well-known forecourt. A rushed fill en route to Wolverton with a train to catch. A new-to-you diesel Volkswagen Passat, its first fuelling, and a driver used to petrol: precisely when it takes place. With rain, a call arriving, or a car full of children to deal with, the hand simply does what it always has.
How to prevent petrol in a diesel on your next fill-up around Old Stratford
- The label is what counts, so read the pump instead of the colour: in the UK unleaded handles are usually green and diesel black, but not on every forecourt.
- The first fill in a new car is the time to check the filler flap — on it, or on the cap, many vehicles state which fuel they take.
- Good intentions count for less than a sticker or a fob in a vivid colour on the diesel's key when a house has one of each. So mark it.
- Say it before you lift it. On the first fill in a new or hired car, say "diesel" aloud before you lift the nozzle off the pump. It sounds daft and it does the trick.
- Thinking about something else is when this becomes an easy mistake to make, and so put your phone away then keep your mind on the petrol pump.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler built to reject a petrol nozzle, and add-on devices exist for vehicles without one. They are a safety net, not a reason to stop reading the petrol pump.
- Spotting it mid-fill? Stop at once. A weaker mixture follows from less petrol inside the tank, but your next step remains the same: do not start the vehicle.
Old Stratford: already put petrol in a diesel?
Then the order of things is brief. Starting it is out, and so is turning on the ignition. Ask the attendants to help you roll it clear of the pump if you are still at the forecourt, whether that's Esso or somewhere else. Next, 0333 366 0103. We'll ask what was put in, about how much, and if it has been run.
Corrosion and deposits are the problem with AdBlue, where petrol means lost protection. So if it was AdBlue, say so — and read its own Old Stratford page.
Why one petrol in a diesel task around Old Stratford costs more than another
A fair single quote doesn't exist here: four situations, four separate jobs. What moves your cost is mostly which of them you are in. Two things follow that: the petrol that was put in as a share of what the tank takes, then the spot the car is in and whether a van can get to it safely.
That's why our technicians ask three questions before costing rather than after: what got in, how much, and whether it has run. A range turns into a straight figure when the answers are in.
About Old Stratford itself
Old Stratford is a village in Northamptonshire, situated on the banks of the River Great Ouse at an elevation of 76 metres. Old Stratford lies near the border with Buckinghamshire, close to the nearby towns of Stony Stratford and Milton Keynes. Old Stratford has a mix of housing types, with semi-detached homes being particularly prevalent. Old Stratford is located approximately 49.7 miles northwest of London, making it a commuter-friendly location.
Across Northamptonshire and around Old Stratford: fuel drain cover
Our vans answering petrol in diesel jobs in Old Stratford, in the MK postcode area, also work the places around it, Stony Stratford, Passenham and Cosgrove included. A forecourt, a supermarket car park, a lay-by or your own drive are all spots we work, and the vehicle does not need to move to us.
Still at the pump in Old Stratford?
Then you are in the best spot there can be. Keep it off. Call.